Coincidence gate ink jet with increased operating pressure window

ABSTRACT

In a coincidence vector gate ink jet, a droplet is expressed from an outlet orifice by a coincident pressure produced by a pair of transducers at an outlet orifice. In this type of ink jet, it is normal for one of a cooperating pair of transducers to be activated in a non-coincident mode. In the non-coincident mode, a droplet is not expressed from an outlet orifice as long as the pressure produced by the one transducer remains below a given threshold. A pressure absorbing chamber is provided, which permits this threshold pressure to be sustantially increased to a level substantially above the minimum coincident pressure produced by the pair of transducers to express a droplet from the orifice. This increase in the threshold pressure is an increase in the operating window. A greater operating window permits greater latitudes in manufacturing variation and permits greater latitudes in pressure variation to change the size of a droplet to effect halftoning.

DESCRIPTION OF INVENTION

This invention relates to a coincidence vector gate ink jet.

Coincidence vector gate ink jets are ink jets which rely upon activationof a particular two transducers to produce a coincident pressureincrease at an orifice to express an ink droplet from the orifice. Whenonly one of the transducers is activated in a non-coincident mode, adroplet will not be expressed from the orifice unless a given maximumpressure threshold for one transducer is surpassed. A minimum pressurein each transducer must be maintained to guarantee a droplet when bothtransducers are activated in the coincident mode. At the present time,the operating window between the maximum and minimum pressures is verylimited, not allowing to a significant degree for manufacturingvariations or allowing for varying the droplet expression pressures tochange the size of droplets for half toning.

It is an object of this invention to increase the window in operatingpressures between a threshold maximum pressure for each transducer and aminimum pressure for each transducer in coincidence vector gate inkjets.

Other objects of the invention will become apparent from the followingdescription with reference to the drawings wherein:

FIG. 1 is a cutaway view of a sample ink jet assembly illustrating acoincidence gate principle;

FIG. 2 is a view taken along section line 2--2 of FIG. 1;

FIG. 3 is a modification of the embodiment of FIGS. 1 and 2 illustratingthe principle of this invention;

FIG. 4 is a plan view of a linear array ink jet assembly;

FIG. 5 is a view taken along section line 5--5 of FIG. 4;

FIG. 6 is a schematic fluid circuit for the ink jet array of FIGS. 4 and5;

FIG. 7 is a schematic of a typical electronic driver electricallyconnected to a piezoelectric member;

FIG. 8 is a modification of the embodiment of FIGS. 4 and 5;

FIG. 9 is a view taken along section line 9--9 of FIG. 8;

FIG. 10 is a view of another modification of the embodiment of FIGS. 4and 5;

FIG. 11 is a view taken along section line 11--11 of FIG. 10;

FIG. 12 is a partial plan view of still another modification of theembodiment of FIGS. 4 and 5;

FIG. 13 is a view taken along section line 13--13 of FIG. 10;

FIG. 14 is a partial plan view of a modification of the embodiment ofFIGS. 12 and 13;

FIG. 15 is a view taken along section line 15--15 of FIG. 14;

FIG. 16 is a partial plan view of another modification of the embodimentof FIGS. 12 and 13;

FIG. 17 is a view taken along section line 17--17 of FIG. 16;

FIGS. 18a and 18b are views of a different embodiment of a linear inkjet array incorporating the principles of this invention;

FIG. 19 is a view taken along section line 19--19 of FIG. 18;

FIGS. 20a and 20b are views of a modification of the embodiment of FIGS.18a, b and 19;

FIG. 21 is a partial plan view of a modification of the embodiment ofFIGS. 18a, b and 19.

FIG. 22 is a view along section line 22--22 of FIG. 21;

FIG. 23 is a partial plan view of another modification of the embodimentof FIGS. 18a, b and 19;

FIG. 24 is a view taken along section line 24--24 of FIG. 23;

FIG. 25 is a partial plan view of yet another modification of theembodiment of FIGS. 18a, b and 19;

FIG. 26 is a view taken along section line 26--26 of FIG. 25;

FIG. 27 is a partial plan view of a modification of the embodiment ofFIGS. 25 and 26; and

FIG. 28 is a view taken along section line 28--28 of FIG. 27.

Referring to FIG. 1, a cutaway view of a housing member 10 of an ink jethousing assembly is shown illustrating the principles of a coincidencegate ink jet. A pair of transducer chambers X_(a) and Y_(a) is providedin the member 10. Fluid pressure passages 12 and 14 lead from thechambers X_(a), Y_(a), respectively, to a liquid ink supply rectifierpassage 16 where the three passages intersect. The liquid ink supplypassage 16 is communicated to a port 18 which in turn is communicatedthrough a conduit 20 to an ink supply reservoir 22, located remotelyfrom the housing, which comprises a sealed flexible bag. Also, at theintersection is an outlet orifice 24 through which ink droplets 26 areexpressed onto a copy medium.

Referring to FIG. 2, the chambers and passages are sealed by a flatflexible layer 28 bonded to the member 10. The transducer chambersX_(a), Y_(a) are fluid tight except for passages 12 and 14 communicatingtherewith. The transducer chambers and passages 12, 14 and 16 arecompletely filled with liquid ink. A piezoelectric ceramic member 30 issandwiched between and bonded to a pair of electrodes 32 and 34 with theelectrode 32 being bonded to the layer 28 thereby effectively bondingthe piezoelectric member 30 thereto. The piezoelectric member 30 ispolarized during the manufacture thereof to contract in a plane parallelto the plane of the flexible layer 28 when excited by applying a voltagepotential across the conductive members 32 and 34. Contraction of thepiezoelectric member 30 will cause the flexible layer 28 to buckleinwardly, thereby decreasing the volume in its respective chamber andeffecting pressure on the liquid ink therein. The members 10 and 28 ofthe housing may be glass or plastic.

When the piezoelectric member for either transducer X_(a) or Y_(a) isactivated, a fluid pressure pulse will occur in a respective one ofpassages 12 and 14 causing displacement of ink along the respectivepassage. The passages 12 and 14 are at such an angle relative to theorifice 24, the impedance to liquid flow in passage 16 relative to theimpedance to liquid flow in orifice 24, and the magnitude and durationof a pressure pulse exerted by the transducer chambers X_(a), Y_(a) aredesigned that the ink stream expressed from only one passage at a timewill entirely miss orifice 24 and displace ink in the ink supply passage16 while the ink within orifice 24 will not be disturbed to the extentof expressing a droplet therethrough. The orifice 24 is located relativeto the intersection of the passages 12, 14 and the magnitude andduration of the pressure pulse exerted by the transducer chambers X_(a),Y_(a) are so designed that the summation vector of the fluid momentumvectors in passages 12 and 14 will lie on the axis of the orifice 24.Thus, only when the piezoelectric members for both transducer chambersX_(a), Y_(a) are activated in a manner that pressure pulses generated bythe respective transducers coincide at a location from the intersectionof passages 12, 14 to the orifice 24 will an ink droplet 26 be expressedfrom orifice 24. It should be understood that the peaks of the pressurepulses generated by both transducers do not necessarily coincide betweenthe intersection of passages 12 and 14 and the orifice 24, but theremust be at least an overlap of the pressure pulses thereat. In thisillustration, the orifice is hydraulically equal distance from eachtransducer chamber, and the piezoelectric members for both transducerswill be simultaneously or coincidentally activated.

Since the transducer chambers are fluid tight except for the passages 12and 14 communicating therewith, at the termination of a pressure pulse,ink is drawn into the passage 12 or 14 from which ink was expressed. Ifa pulse is applied to only one of the passages 12, 14, then most of theink expressed therefrom will be drawn back into the passage with theremainder of the ink drawn into the passage being supplied from supplypassage 16. If a pulse was applied to both passages 12, 14simultaneously, resulting in an ink droplet being expressed from orifice24, then ink from supply passage 16 will be drawn into both passages 12,14 after pulse termination. Thus, the ink within the pressure chambersX_(a), Y_(a) and most of passages 12, 14 is stagnant or confined thereinand acts only as a mechanical ram for expressing ink droplets throughthe orifice 24 with the ink forming the droplets being supplied from thereservoir 22.

When only one of the transducers X_(a), Y_(a) is activated in anon-coincident mode, a droplet will not be expressed from the orifice 24unless a given pressure threshold is surpassed. For instance, if ittakes 100 psi to express a droplet when the two transducers X_(a), Y_(a)are activated in a coincident mode to produce a coincident pressureincrease at the orifice, only 50 psi need be produced by each transducerX_(a), Y_(a). Also, a pressure increase by only one transducer in anon-coincident mode of approximately 100 psi (threshold) will alsoproduce a droplet from orifice 24. Thus, the maximum pressure exerted byone transducer in a noncoincident mode must be maintained belowthreshold, or in this case, approximately 100 psi. The minimum pressuremust be maintained at 50 psi to assure expression of a droplet fromorifice 24 when both transducers are activated in a coincident mode.Thus, the operating window between the maximum and minimum pressures isvery limited, not allowing to a significant degree for manufacturingvariations or for varying the droplet expression pressures to change thesize of droplets for half-toning. An ink droplet size varies with thedroplet expression pressure. To half-tone, it is desirable tosignificantly vary the pressure and thereby the drop size. Theexpression pressure may vary from 100 psi to 500 psi or more. This meansthat, at the maximum pressure, each transducer X_(a), Y_(a), in acoincident mode, must effect a pressure of approximately 250 psi eachand still not express a droplet through orifice 24 when only onetransducer is activated, in a non-coincident mode, although a combinedpressure of 100 psi will produce such a droplet. The principle of thisinvention is directed toward opening the operating window and isexplained with reference to FIG. 3.

Referring to FIG. 3, all elements which are the same as the embodimentof FIG. 1 are designated by the same reference numerals. A pressureabsorption chamber 100 is aligned with the passage 12 and located on oneside of orifice 24 and a pressure absorption chamber 102 is aligned withthe passage 14 and located on the opposite side of the orifice 14.Elastic membranes 104 and 106 seal the outer opening of the chambers 100and 102, respectively. The membrane 104 may be a thin (1 to 2 mil) Mylarfilm or other similar flexible material. Each time there is a pressureincrease in passage 12 alone, a jet stream will be directed to thealigned chamber 100. The membrane 104 is designed to stretch underpressure to render the chamber 100 a path of least resistance comparedto the resistance of the droplet orifice 24 and meniscus formed therein.Since the stream from inlet passage 12 is aligned with the pressureabsorption chamber 100, the stream is in shear with the fluid in dropletorifice 24 and a majority of the pressure increase will be absorbed inthe absorption chamber 100 by the expansion of the membrane 104. Whenpassage 14 is pressurized, the absorption chamber 102 and elasticmembrane 106 act in the same manner as chamber 100 and membrane 104 toabsorb a substantial portion of the pressure increase in passage 14 witha very small proportion thereof being transmitted to the liquid in theoutlet orifice 24.

The provision of pressure absorption chambers 100 and 102 allows asubstantial pressure to be produced by either transducer X_(a), Y_(a) ina non-coincident mode without expressing a droplet from orifice 24, butyet the pressure for expressing a droplet from orifice 24 by acoincident increase of pressure at the orifice from both transducerswill be substantially less. For instance, a combined coincident pressurefrom both transducers required to express a droplet can be designed tobe approximately 100 psi or 50 psi each. However, the maximum pressureproduced by one transducer before expressing a droplet may be as high as250 psi or more due to the provision of the pressure absorbing chamber.Thus, the operating window has been opened where greater latitude withmanufacturing variations is possible and a greater latitude of dropletexpression pressures is possible for changing the size of a droplet forhalf-toning.

The coincidence gate principle in combination with the principle forincreasing power differential can be incorporated in an array of inkjets as shown in FIGS. 4 and 5. All elements which are the same as theprevious embodiments are designated by the same reference numerals. Aglass or plastic housing comprises three members 44, 45 and 46 securedby screws 48. The member 44 has nine channels forming fluid pressurepassages 50, 52, 54, 56, 58, 60, 62, 64 and 66. The member 46 has ninechannels forming fluid pressure passages 70, 72, 74, 76, 78, 80, 82, 84and 86. Located in the member 44 are fluid transducer chambers X_(a),Y_(b), and X_(c), located in member 46 are fluid transducer chambersY_(a), Y_(b) and Y_(c). The chamber X_(a) is communicated to pressurepassages 50, 52, and 54 by inlet passages 88, 90 and 92, respectively.Chamber X_(b) is communicated to pressure passages 56, 58 and 60 byinlet passages 94, 96 and 98, respectively. Chamber X_(c) iscommunicated to pressure passages 62, 64 and 66 by inlet passages 101,103 and 105, respectively. Chamber Y_(a) is communicated to pressurepassages 70, 76 and 82 by inlet passages 106, 108 and 110, respectively.Chamber Y_(b) is communicated to pressure passages 72, 78 and 84 byinlet passages 112, 114 and 116, respectively. Chamber Y_(c) iscommunicated to pressure passages 74, 80, and 86 by inlet passages 118,120 and 122, respectively.

At the front end of each of the pressure passages 50, 52, 54, 56, 58,60, 62, 64 and 66 in member 44 is an orifice inlet passage 12 and at thefront end of each of the pressure passages 70, 72, 74, 76, 78, 80, 82,84 and 86 is an orifice inlet passage 14. A supply passage 124 islocated in member 44 and extends in a direction transverse to thepressure passages, and a supply passage 126 is located in member 46 andextends also in a direction transverse to the pressure passages.Orifices 24 are aligned with each pair of inlet passages 12 and 14. Aplurality of laterally spaced vertical fluid rectifier passages 128 arecommunicated at one end to the passage 124 and at the other end topassage 126 and are located to provide a fluid rectifier layer betweeneach orifice and the intersection of a pair of orifice inlet passages12, 14. Referring to FIG. 4, a fluid supply inlet 132 communicates avertical passage 130 with a fluid reservoir (not shown). The verticalpassage 130 is communicated to laterally extending vertically spacedpassages 124, 126 to provide a fluid supply path therefor. A verticalpassage 133 communicates the end of the passages 124 and 126 with eachother.

The following pairs of pressure passages are communicated with theorifices of the following jets: passages 70 and 50 with jet 146;passages 72 and 52 with jet 148; passages 74 and 54 with jet 150;passages 76 and 56 with jet 152; passages 78 and 58 with jet 154;passages 80 and 60 with jet 156; passages 82 and 62 with jet 158;passages 84 and 64 with jet 160; and passages 86 and 66 with jet 162.

Referring to FIG. 6, a schematic fluid circuit is illustrated for thearray of nine coincidence gate ink jets disclosed in FIGS. 4 and 5. Sixelectrical input drivers X₁, X₂, X₃, Y₁, Y₂ and Y₃ are electricallyconnected to a piezoelectric member of transducer chambers X_(a), X_(b),X_(c), Y_(a), Y_(b) and Y_(c), respectively, by a respective one ofelectrical lines 134, 136, 138, 140, 142 and 144.

Referring to FIG. 7, there is illustrated a piezoelectric member 30electrically connected to a typical electronic driver which is a NPNtype transistor in an emitter follower configuration driven between anon-conductive state and a state of saturated conduction in response topositive going pulse-like input signals supplied to the base of thetransistor. All of the electronic drivers are electrically connected totheir respective piezoelectric members in the same manner.

The transducer chambers, conduits and pressure inlets as well as pulseduration and magnitude are all designed that the hydraulic properties ateach ink jet are the same. Since an orifice may be hydraulically unequaldistance away from the two transducers to which it is communicated, thetransducers, in actual practice, will be activated out of phase witheach other so the pressure pulse generated by each transducer will occurcoincidentally at a location from the intersection of the pressureinlets 12, 14 to the orifice 24. The following table shows which jetsexpress droplets therefrom when particular drivers are energized:

    ______________________________________                                        Transducers        Droplet Expressed                                          Cooperatively Activated                                                                          From Jet                                                   ______________________________________                                        X.sub.a, Y.sub.a   146                                                        X.sub.a, Y.sub.b   148                                                        X.sub.a, Y.sub.c   150                                                        X.sub.b, Y.sub.a   152                                                        X.sub.b, Y.sub.b   154                                                        X.sub.b, Y.sub.c   156                                                        X.sub.c, Y.sub.a   158                                                        X.sub.c, Y.sub.b   160                                                        X.sub.c, Y.sub.c   162                                                        ______________________________________                                    

The principle of this invention is incorporated in the ink jet array byproviding pressure absorption passages 100, 102 on each side of theorifice 24 for each jet. The absorption passage 100 is aligned with thepressure inlet passage 14 and the absorption passage 102 is aligned withthe pressure inlet passage 12. A membrane 104 extends in a lateraldirection across the array of jets and is sealed to the front face ofthe housing member 44 to seal each chamber 100 from the exterior andprovide an absorption member. A membrane 106 extends in a lateraldirection across the array of jets and is sealed to the front face ofthe member 46 to seal each chamber 102 from the exterior and provide anabsorption member. The absorption chambers 100 and 102 operate in thesame manner as described for the embodiment of FIG. 3.

Referring to FIGS. 8 and 9, the same construction of the invention isshown incorporated in a fluid rectifier configuration which is differentthan the embodiment of FIGS. 4 and 5. All elements which are the same asin the embodiment of FIGS. 4 and 5 are designated by the same referencenumerals only with an "a" affixed thereto. In this embodiment, thereservoir (not shown) is connected to port holes 200 and 202 whichcommunicates the reservoir to a laterally extending chamber 204.

Referring to FIGS. 10 and 11, the same construction of the invention isshown incorporated in an embodiment in which the fluid rectifier iseliminated. All elements which are the same as in the embodiment ofFIGS. 4 and 5 are designated by the same reference numerals only with a"b" affixed thereto. In this embodiment, each fluid chamber is directlyconnected with a reservoir (not shown) through fluid supply inletpassages 210. A laterally extending chamber 212 extends between theorifices 24b and the intersection of pressure inlet passages 12b and 14bof each jet. In this particular instance, the fluid in the chamber 212absorbs some pressure along with the pressure absorption chambers 100band 102b.

Referring to FIGS. 12 and 13, a different type of pressure absorptionchamber is shown for applying the principle of this invention. Allelements which are the same as in the embodiment of FIGS. 4 and 5 aredesignated by the same reference numerals, only with a "c" affixedthereto. The reservoir (not shown) is connected to port holes 300 and302 which communicates the reservoir to a laterally extending rectifierchamber 304. A vertical cylindrical pressure absorbing chamber 306 isprovided for each orifice. Each chamber 306 descends from the top outersurface 308 through the rectifier chamber 304 and through the bottomouter surface 310. A laterally extending flexible membrane 312 extendsacross all of the top openings of chambers 306 and is sealed to the topsurface 308 of member 44c and a flexible membrane 314 extends across allof the bottom openings of chambers 310 and is sealed to the bottomsurface 310 of member 46c. A stream expressed from either pressure inlet12c or 14c will strike the wall of the chamber 306 which will produce achurning with a generally resultant vertical force in the chamber 306being absorbed by stretching of either membrane 312 or 314 dependingupon from which pressure inlet passage 12c or 14c the stream isexpressed.

Referring to FIGS. 14 and 15, the same pressure absorbing chamberarrangement as in FIGS. 12 and 13 is shown, only each fluid chamber isdirectly connected to the fluid reservoirs (not shown) as in theembodiment of FIGS. 8 and 9. All elements which are the same as theembodiment in FIGS. 10 and 11 are designated by the same referencenumerals only with a "d" affixed thereto. A laterally extending chamber320 extends between the orifices 24d and the intersection of pressureinlet passages 12d and 14d of each jet. In this particular embodiment,the fluid in chamber 320d absorbs some pressure along with the pressureabsorption chambers 306d.

Referring to FIGS. 16 and 17, those elements which are the same as inthe embodiment of FIGS. 12 and 13 are designated by the same referencenumerals, only with an "e" affixed thereto. The same pressure absorbingchamber arrangement in FIGS. 14 and 15 is shown, only the lateralchamber 320 between the orifices 24d and the intersection of pressurepassages 12d and 14d has been removed.

In all the embodiments disclosed the present invention has beenincorporated in an ink jet array where the pressure inlet passages 12and 14 converge in a vertical plane or, in other words, a planetransverse to the plane of the jet array. This invention may also beapplied to ink jet arrays where the pressure inlet passages 12 and 14converge in a horizontal plane, or in other words, in the same plane asor a plane parallel to the plane of the jet array. An embodimentdisclosing this type of jet array is shown in FIGS. 18a, 18b, and 19. Afour jet array is shown for simplicity, it being sufficient forillustrating the incorporation of the coincidence gate principle and thepressure absorbing principle. A glass or plastic housing comprises twomembers 400, 402 secured together by screws 404. The member 400 has fivechannels forming fluid pressure passages 406, 408, 410, 412 and 414.Located in member 400 are fluid transducer chambers C₁ and C₂, andlocated in member 402 are fluid transducer chambers D₁ and D₂. Thechamber C₁ is communicated to pressure passages 406 and 414 by inletpassages 416 and 418, respectively. Chamber C₂ is communicated topressure passage 412 by inlet passage 420. Chamber D₁ is communicated topressure passage 410 by inlet passage 422. Chamber D₂ is communicated topressure passage 408 by inlet passage 424. The pressure passages 406 and414 each feed into an orifice inlet passage 426 and 428, respectively.The pressure passage 408 feeds into two orifice inlet passages 430 and432. Referring to FIG. 18b, the pressure passage 410 feeds into twoorifice inlet passages 434 and 436, and the pressure passage 412 feedsinto two orifice inlet passages 438 and 440. The pair of orifice inletpassages 426 and 430 intersect each other opposite an orifice 442; thepair of orifice inlet passages 432 and 434 intersect each other oppositean orifice 444; the pair of orifice inlet passages 434 and 436 intersecteach other opposite an orifice 446; and a pair of orifice inlet passages440 and 428 intersect each other opposite an orifice 448.

A fluid rectifier chamber 450 extends laterally across the array oforifices and provides a fluid layer between the intersection of eachpair of orifice inlet passages and a respective orifice. The rectifierchamber 450 is communicated at one end to a fluid supply passage 452located in member 400 and at the other end to a fluid supply passage454, also located in member 400, which fluid supply passages are joinedtogether by a laterally extending supply passage 456 located in member400. A downwardly extending inlet passage 458 in member 400 is connectedto the passage 456 and connected to a fluid supply reservoir (not shown)to communicate the reservoir with the rectifier chamber 450. Eachtransducer is operated by a piezoelectric member as in the previousembodiments with the same elements thereof as described in theembodiment of FIGS. 1 and 2 being designated by the same referencenumerals. Each outlet orifice has a pair of pressure absorption chamberslocated on each side thereof with each absorption chamber being alignedwith a respective orifice inlet passage. A pair of pressure absorptionchambers 460 and 462 are associated with orifice 442 and are alignedwith orifice inlet passages 430 and 426, respectively. Absorptionchambers 464 and 466 are associated with orifice 444 and are alignedwith orifice inlet passages 434 and 432, respectively. Absorptionchambers 468 and 470 are associated with orifice 446 and are alignedwith orifice inlet passages 438 and 436, respectively, and absorptionchambers 472 and 474 are associated with the orifice 448 and are alignedwith orifice inlet passages 428 and 440, respectively. Thin flexiblemembranes 476, 478, 480, 482 and 484 are adhered to the housing to sealthe pressure absorption chambers from the exterior thereof and toprovide a pressure absorbing member.

The coincidence gating of this embodiment is the same as the otherembodiments with droplets being expressed from the orifices inaccordance with the following:

    ______________________________________                                        Transducers        Droplet Expressed                                          Cooperatively Engaged                                                                            From Jet                                                   ______________________________________                                        C.sub.1, D.sub.2   442                                                        D.sub.2, D.sub.1   444                                                        D.sub.1, C.sub.2   446                                                        C.sub.2, C.sub.1   448                                                        ______________________________________                                    

Referring to FIGS. 20a and 20b, the same type of ink jet array is shownas in FIGS. 16 and 17, only the fluid supply reservoir is not connectedto the fluid layer 500 between the orifices and the intersection of theorifice inlet passages. Fluid supply refill is provided directly to thetransducer chambers. In this embodiment all elements which are the sameas the embodiment of FIGS. 18 and 19 are designated by the samereference numerals, only with an "f" affixed thereto. A pair of supplypassages 502 and 504 are communicated with the reservoir (not shown) bypassage 456F which intersects both passages. Passages 506 and 508 extendupwards from the supply passage 502 into the transducer chambers C₁ fand C₂ f, respectively. Passages 510 and 512 extend downwards from thesupply passage 504 into the transducer chambers D₁ f and D₂ f,respectively.

Referring to FIGS. 21 and 22, a modification of the embodiment of FIGS.18 and 19 is illustrated. All elements which are the same as in theembodiment of FIGS. 16 and 17 are designated by the same referencenumeral, only with a "g" affixed thereto. In this embodiment a pair ofvertically spaced laterally extending fluid rectifier supply passages520 and 522 are communicated with the fluid supply passages 452g and454g by vertical passages 524 and 526, respectively. Four laterallyspaced vertical energy absorption chambers 528, 530, 532 and 534 arecommunicated with the laterally extending passages 520, 522 and arelocated between a respective orifice 442g, 444g, 446g, 448g and arespective intersection of the orifice inlet passages. A flexiblemembrane 535 spans across the top of the housing 400g and a flexiblemembrane 538 spans across the bottom of the housing 402g to seal off theenergy absorbing chambers from the exterior. When only the pressure isincreased in one orifice inlet passage of a cooperative pair, a jetstream will miss the orifice and strike a wall 536 on a particular sideof the orifice with the resultant turbulence effected thereby beingabsorbed by the portion of the membranes 535 and 538 associatedtherewith. The separate absorption chambers also reduce cross talkbetween the orifices.

Referring to FIGS. 23 and 24, a modification of FIGS. 18 and 19 isshown. All elements which are the same as the embodiment of FIGS. 18 and19 are designated by the same reference numerals only with an "h"affixed thereto. In this embodiment the fluid reservoir is connecteddirectly with the transducer chambers. A plurality of laterally spaced,vertically extending pressure absorbing chambers 540, 542, 544 and 546are located between a respective orifice and intersection of arespective pair of orifice inlet passage means. A flexible membrane 548spans across the top of housing 400h and a flexible membrane 550 spansacross the bottom of the housing 402h to seal off the pressure absorbingchambers from the exterior. When pressure is increased in one orificeoutlet passage of a cooperative pair, a jet stream will miss the orificeand strike a wall 552 on a particular side of the orifice with aresultant pressure surge and turbulence effected thereby beingtransmitted to the absorbing chamber and absorbed by the portion of themembranes 548 and 550 associated therewith.

Referring to FIGS. 25 and 26, there is illustrated still anothermodification of FIGS. 18 and 19. All elements which are the same as theelements in the embodiment of FIGS. 18 and 19 are designated by the samereference numerals, only with an "i" affixed thereto. In this particularembodiment, a plurality of laterally spaced vertically extendingpressure absorbing chambers 560, 562, 564, 566 and 568 are incommunication with the fluid rectifier chamber 450i. The chambers 562,564 and 566 are located between a respective pair of orifices and thechambers 560 and 568 are located to one side of orifices 442i and 448i,respectively. A flexible membrane 570 spans across the top of thehousing 400i and a flexible membrane 572 spans across the bottom of thehousing 402i to seal off the pressure absorbing chambers from theexterior. When the pressure is increased in one orifice outlet passageof a cooperative pair, a jet stream will miss the orifice and strike awall 574 of the fluid rectifier chamber with a resultant pressure surgeand turbulence effected thereby being partially transmitted to theabsorbing chamber and absorbed by the portion of the membranes 570 and572 associated therewith. In this particular embodiment, the fluid inchamber 450i absorbs some pressure along with the pressure absorptionchambers.

Referring now to FIGS. 27 and 28, a modification of the embodiment ofFIGS. 25 and 26 is illustrated. All elements which are the same as inthe embodiment of FIGS. 25 and 26 are designated by the same referencenumerals, only with a "j" affixed thereto. This embodiment differs fromthe embodiment of FIGS. 25 and 26 in that the fluid supply from thereservoir is fed directly to the transducer chambers. A fluid layer inchamber 600 is provided between the intersection of the intersections ofthe orifice passages and the orifices. The chambers 560j, 562j, 564j,566j and 568j and the chamber 600 act together as a pressure absorbingunit.

Obviously, some embodiments are not as efficient a pressure absorber asother embodiments, but the operating window is still significantlyincreased. Furthermore, the membrane sealing the pressure absorbingchambers could be eliminated. In this instance, the maximum pressureabsorbed by the chamber would be controlled by the meniscus tension inthe chamber, as the pressure would have to be kept below a level whichcould cause ink droplet expression through the unsealed chamber opening.Obviously, this construction would not be as efficient as a constructionwhich includes the membrane, but the operating window would still besignificantly increased.

It should be realized that each transducer does not have to producesubstantially equal pressures, but one may produce a major portion ofthe coincident pressure required to express a droplet.

What is claimed is:
 1. A coincidence gate ink jet comprising: an outletorifice, a first transducer chamber, a second transducer chamber, firstpassage means communicating said first transducer chamber to saidorifice, second passage means communicating said second transducerchamber to said orifice, said first and second passage meansintersecting each other adjacent said orifice, the axis of each of saidfirst and second passage means at said intersection being at an anglewith the axis of said orifice, pressure absorbing chamber meanscommunicated with said orifice and intersection, means for allowingfluid displacement in said absorbing chamber means when only onetransducer is actuated, said pressure absorbing chamber means being sodesigned and arranged relative to said intersection and said orificethat the minimum pressure required to express a droplet through saidorifice upon actuation of only one of said transducers will be increasedcompared to the minimum pressure required to express a droplet from theorifice of a similar ink jet structure without the absorbing chambermeans.
 2. The structure as recited in claim 1 wherein said means forallowing fluid displacement in said absorbing chambers comprises anopening in each of said absorbing chambers and an elastic membranesealing a respective said opening in a respective said absorbingchamber.
 3. A coincidence gate ink jet comprising: an outlet orifice, afirst transducer chamber, a second transducer chamber, first passagemeans communicating said first transducer chamber to said orifice,second passage means communicating said second transducer chamber tosaid orifice, said first and second passage means intersecting eachother adjacent said orifice, the axis of each of said first and secondpassage means at said intersection being at an angle with the axis ofsaid orifice, a pair of pressure absorbing chambers, one of saidpressure absorbing chambers being on one side of said orifice and beinggenerally aligned with said first passage means, the other of saidpressure absorbing chambers being on the opposite side of said orificeand being generally aligned with said second passage means, and meansfor allowing fluid displacement in said absorbing chambers, whereby theminimum pressure required to express a droplet through said orifice uponactuation of only one of said transducers will be increased compared tothe minimum pressure required to express a droplet from the orifice of asimilar ink jet structure without the absorbing chambers.
 4. Thestructure as recited in claim 3, wherein said means for allowing fluiddisplacement in said absorbing chambers comprises an opening in each ofsaid absorbing chamber means and an elastic membrane sealing arespective said opening in a respective said absorbing chamber.
 5. Thestructure as recited in claim 3 further comprising a fluid chamber incommunication with and interposed between said intersection and saidorifice.
 6. The structure as recited in claim 5 wherein said fluidchamber is communicated to a fluid supply reservoir.
 7. An array ofcoincidence gate ink jets comprising: a housing, a plurality oflaterally spaced apart outlet orifices in said housing, each of saidorifices having first and second orifice inlet passages communicatedtherewith, said first and second inlet passages intersecting each otheradjacent said orifice, the axis of each of said first and second inletpassages at said intersection being at an angle with the axis of itsrespective said orifice, pressure absorbing chamber means for eachorifice adjacent said intersection and aligned with one of said passagemeans, means for allowing fluid displacement in said absorbing chambermeans, whereby the minimum pressure required to express a dropletthrough a respective said orifice upon an increase in pressure in saidone inlet passage will be increased compared to the minimum pressurerequired to express a droplet from the orifice of a similar ink jetstructure without the absorbing chambers.
 8. The structure as recited inclaim 7 wherein said means for allowing fluid displacement in saidabsorbing chamber means comprises an opening in each of said absorbingchamber means and an elastic membrane sealing a respective said openingin a respective said absorbing chamber.
 9. The structure as recited inclaim 7 wherein the axes of a respective said first and second inletpassages of said intersection are generally in a plane which isgenerally transverse to the lateral direction in which said outletorifices are spaced apart, and the axis of a respective said absorptionchamber means is generally in said plane.
 10. The structure as recitedin claim 8 wherein the axes of a respective said first and second inletpassages at said intersection are generally in a plane which isgenerally transverse to the lateral direction in which said outletorifices are spaced apart, and the axis of a respective said absorptionchamber means is generally in said plane.
 11. The structure as recitedin claim 10 further comprising fluid chamber means in communication withand interposed between at least each of said intersections and arespective said orifice.
 12. The structure as recited in claim 11wherein said fluid chamber means comprises a plurality of spaced apartchambers, one for each orifice.
 13. The structure as recited in claim 12wherein said fluid chamber means is communicated to a fluid supplyreservoir.
 14. The structure as recited in claim 7 wherein the axes of arespective said first and second inlet passage at said intersection isgenerally in a plane which is generally parallel to the lateraldirection in which said outlet orifices are spaced apart, and the axisof a respective said absorption chamber means is generally in saidplane.
 15. The structure as recited in claim 8 wherein the axis of arespective said first and second inlet passage at said intersection isgenerally in a plane which is generally parallel to the lateraldirection in which said outlet orifices are spaced apart, and the axisof a respective said absorption chamber means is generally in saidplane.
 16. The structure as recited in claim 15 further comprising fluidchamber means in communication with and interposed between at least eachof said intersections and a respective said orifice.
 17. The structureas recited in claim 16 wherein said fluid chamber means comprises aplurality of spaced apart chambers, one for each orifice.
 18. Thestructure as recited in claim 17 wherein said fluid chamber means iscommunicated to a fluid supply reservoir.